With an aging population and changes in life environment, the development of an orally-disintegrating solid preparation, which can be taken easily and readily at any time and anywhere without taking water, and which retains convenience of handling characterizing tablets, is desired.
On the other hand, when a physiologically active substance is a substance having a bitter taste, masking of the bitter taste by coating is preferable for drug compliance. Also, when the physiologically active substance is easily decomposed by an acid, it is necessary to coat the ingredient to prevent decomposition by the gastric acid and ensure sufficient delivery to the intestine. To solve these problems, coated tablets, capsules and the like are generally used.
To meet these requirements, tablets containing coated fine granules have conventionally been developed. For example, JP-A-6-502194 (U.S. Pat. No. 5,464,632) discloses a rapidly disintegratable multiparticular tablet comprising an effective substance in the form of coated fine particles and the like. In addition, JP-A-2000-281564 and JP-A-2000-103731 disclose orally-disintegrating tablets containing coated fine granules in tablets.
During the production of solid preparations such as tablet containing coated fine granules and the like, however, fine granules may be broken during tableting as evidenced by partial destruction of a coated film of fine granules and the like, resulting in problems such as a decreased masking effect on the aforementioned bitter taste, acid resistance and the like.    patent document 1: JP-A-6-502194    patent document 2: JP-A-2000-281564    patent document 3: JP-A-2000-103731